1 files changed, 71 insertions, 1 deletions

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index e541d7f4b4e0..7a8d67537d3f 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -109,6 +109,73 @@ static const struct file_operations regmap_map_fops = {
 	.llseek = default_llseek,
 };
 
+static ssize_t regmap_access_read_file(struct file *file,
+				       char __user *user_buf, size_t count,
+				       loff_t *ppos)
+{
+	int reg_len, tot_len;
+	size_t buf_pos = 0;
+	loff_t p = 0;
+	ssize_t ret;
+	int i;
+	struct regmap *map = file->private_data;
+	char *buf;
+
+	if (*ppos < 0 || !count)
+		return -EINVAL;
+
+	buf = kmalloc(count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/* Calculate the length of a fixed format  */
+	reg_len = regmap_calc_reg_len(map->max_register, buf, count);
+	tot_len = reg_len + 10; /* ': R W V P\n' */
+
+	for (i = 0; i < map->max_register; i++) {
+		/* Ignore registers which are neither readable nor writable */
+		if (!regmap_readable(map, i) && !regmap_writeable(map, i))
+			continue;
+
+		/* If we're in the region the user is trying to read */
+		if (p >= *ppos) {
+			/* ...but not beyond it */
+			if (buf_pos >= count - 1 - tot_len)
+				break;
+
+			/* Format the register */
+			snprintf(buf + buf_pos, count - buf_pos,
+				 "%.*x: %c %c %c %c\n",
+				 reg_len, i,
+				 regmap_readable(map, i) ? 'y' : 'n',
+				 regmap_writeable(map, i) ? 'y' : 'n',
+				 regmap_volatile(map, i) ? 'y' : 'n',
+				 regmap_precious(map, i) ? 'y' : 'n');
+
+			buf_pos += tot_len;
+		}
+		p += tot_len;
+	}
+
+	ret = buf_pos;
+
+	if (copy_to_user(user_buf, buf, buf_pos)) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	*ppos += buf_pos;
+
+out:
+	kfree(buf);
+	return ret;
+}
+
+static const struct file_operations regmap_access_fops = {
+	.open = regmap_open_file,
+	.read = regmap_access_read_file,
+	.llseek = default_llseek,
+};
 
 void regmap_debugfs_init(struct regmap *map)
 {
@@ -119,9 +186,12 @@ void regmap_debugfs_init(struct regmap *map)
 		return;
 	}
 
-	if (map->max_register)
+	if (map->max_register) {
 		debugfs_create_file("registers", 0400, map->debugfs,
 				    map, &regmap_map_fops);
+		debugfs_create_file("access", 0400, map->debugfs,
+				    map, &regmap_access_fops);
+	}
 }
 
 void regmap_debugfs_exit(struct regmap *map)